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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 10 of 10. This is the beginning of the thread.
Posted by jrbecker76 on July 10, 2008, at 19:29:10
Brain Chemical Shown to Induce both Desire and Dread
7/9/2008Source: Society for Neuroscience
Dopamine's opposing effects separated by a few millimeters in the brain
The chemical dopamine induces both desire and dread, according to new animal research in the July 9 issue of The Journal of Neuroscience. Although dopamine is well known to motivate animals and people to seek positive rewards, the study indicates that it also can promote negative feelings like fear. The finding may help explain why dopamine dysfunction is implicated not only in drug addiction, which involves excessive desire, but in schizophrenia and some phobias, which involve excessive fear.
"This study changes our thinking about what dopamine does," said Howard Fields, MD, PhD, of the University of California, San Francisco, an expert unaffiliated with the study. "There is a huge body of evidence out there to support the idea that dopamine mediates positive effects, like reward, happiness, and pleasure. This study says, it does do that, but it can also promote negative behaviors through actions in an adjacent brain area," Fields said.
Kent Berridge, PhD, and his colleagues at the University of Michigan, identified dopamine's dual effect on the nucleus accumbens, a brain region that motivates people and animals to seek out pleasurable rewards like food, sex, or drugs, but is also involved in fear. They found that inhibiting dopamine's normal function prevented the nucleus accumbens neurons from inducing both rewarding and fearful behaviors, suggesting that dopamine is important in both.
In previous research, Berridge and colleagues showed that a distance of only a few millimeters separated desire and dread functions in the nucleus accumbens (which is only about 5 millimeters long in humans). Because dopamine is an important neurotransmitter in this brain structure, the researchers investigated its role in generating these functions in the current study.
When dopamine was allowed to act normally, injection of a chemical to model normal signaling in the front of the nucleus accumbens caused rats to eat nearly three times as much as they normally do. In contrast, injection of the chemical in the back of the nucleus accumbens caused rats to display fearful behavior normally shown in response to a predator.
"It has always been assumed that discrete neurotransmitters might separate fear from desire, but this report shows that transmitters such as dopamine play a constant role and that the anatomy is providing for emotional discretion," said Peter Kalivas, PhD, at the Medical University of South Carolina, who was unaffiliated with the study.
Berridge speculates that disruption of dopamine neurotransmission in one region of the nucleus accumbens may be a mechanism for pathological excesses of fear in disorders such as schizophrenia, whereas disruptions in dopamine neurotransmission in an adjacent region may be a mechanism for excessive reward-seeking in conditions like addiction.
###
The research was supported by the National Institute of Mental Health and the National Institute on Drug Abuse.
The Journal of Neuroscience is published by the Society for Neuroscience, an organization of more than 38,000 basic scientists and clinicians who study the brain and nervous system. Berridge can be reached at berridge@umich.edu .
Posted by Phillipa on July 11, 2008, at 0:20:27
In reply to Study highlights Dopamine's dichotomous role, posted by jrbecker76 on July 10, 2008, at 19:29:10
Thanks so much. Love Phillipa
Posted by Bob on July 11, 2008, at 14:41:36
In reply to Study highlights Dopamine's dichotomous role, posted by jrbecker76 on July 10, 2008, at 19:29:10
> Brain Chemical Shown to Induce both Desire and Dread
> 7/9/2008
>
> Source: Society for Neuroscience
>
> Dopamine's opposing effects separated by a few millimeters in the brain
>
> The chemical dopamine induces both desire and dread, according to new animal research in the July 9 issue of The Journal of Neuroscience. Although dopamine is well known to motivate animals and people to seek positive rewards, the study indicates that it also can promote negative feelings like fear. The finding may help explain why dopamine dysfunction is implicated not only in drug addiction, which involves excessive desire, but in schizophrenia and some phobias, which involve excessive fear.
>
> "This study changes our thinking about what dopamine does," said Howard Fields, MD, PhD, of the University of California, San Francisco, an expert unaffiliated with the study. "There is a huge body of evidence out there to support the idea that dopamine mediates positive effects, like reward, happiness, and pleasure. This study says, it does do that, but it can also promote negative behaviors through actions in an adjacent brain area," Fields said.
>
> Kent Berridge, PhD, and his colleagues at the University of Michigan, identified dopamine's dual effect on the nucleus accumbens, a brain region that motivates people and animals to seek out pleasurable rewards like food, sex, or drugs, but is also involved in fear. They found that inhibiting dopamine's normal function prevented the nucleus accumbens neurons from inducing both rewarding and fearful behaviors, suggesting that dopamine is important in both.
>
> In previous research, Berridge and colleagues showed that a distance of only a few millimeters separated desire and dread functions in the nucleus accumbens (which is only about 5 millimeters long in humans). Because dopamine is an important neurotransmitter in this brain structure, the researchers investigated its role in generating these functions in the current study.
>
> When dopamine was allowed to act normally, injection of a chemical to model normal signaling in the front of the nucleus accumbens caused rats to eat nearly three times as much as they normally do. In contrast, injection of the chemical in the back of the nucleus accumbens caused rats to display fearful behavior normally shown in response to a predator.
>
> "It has always been assumed that discrete neurotransmitters might separate fear from desire, but this report shows that transmitters such as dopamine play a constant role and that the anatomy is providing for emotional discretion," said Peter Kalivas, PhD, at the Medical University of South Carolina, who was unaffiliated with the study.
>
> Berridge speculates that disruption of dopamine neurotransmission in one region of the nucleus accumbens may be a mechanism for pathological excesses of fear in disorders such as schizophrenia, whereas disruptions in dopamine neurotransmission in an adjacent region may be a mechanism for excessive reward-seeking in conditions like addiction.
>
> ###
>
> The research was supported by the National Institute of Mental Health and the National Institute on Drug Abuse.
>
> The Journal of Neuroscience is published by the Society for Neuroscience, an organization of more than 38,000 basic scientists and clinicians who study the brain and nervous system. Berridge can be reached at berridge@umich.edu .
This would go a long way to explaining the widely varied responses among different individuals, as well as the plethora of side effects some people experience.
Posted by Michael Bell on July 13, 2008, at 15:15:29
In reply to Study highlights Dopamine's dichotomous role, posted by jrbecker76 on July 10, 2008, at 19:29:10
Great post! Makes so much sense
Posted by chiron on July 14, 2008, at 23:06:57
In reply to Re: Study highlights Dopamine's dichotomous role » jrbecker76, posted by Michael Bell on July 13, 2008, at 15:15:29
Finally, some research (at least that I'm aware of) that doesn't generalize/simplify neurotransmitters. I'm sick of hearing "serotonin", and that low doses cause depression. That is only a small piece of the complicated puzzle. This also helps explain different reactions people have, and the changes with different doses.
Posted by Bob on July 15, 2008, at 0:26:00
In reply to Re: Study highlights Dopamine's dichotomous role, posted by chiron on July 14, 2008, at 23:06:57
> Finally, some research (at least that I'm aware of) that doesn't generalize/simplify neurotransmitters. I'm sick of hearing "serotonin", and that low doses cause depression. That is only a small piece of the complicated puzzle. This also helps explain different reactions people have, and the changes with different doses.
Yeah. Now all that has to happen is for someone to let the drug companies and doctors (some of them) know.
Posted by blueboy on July 15, 2008, at 10:34:57
In reply to Re: Study highlights Dopamine's dichotomous role, posted by chiron on July 14, 2008, at 23:06:57
> Finally, some research (at least that I'm aware of) that doesn't generalize/simplify neurotransmitters. I'm sick of hearing "serotonin", and that low doses cause depression. That is only a small piece of the complicated puzzle. This also helps explain different reactions people have, and the changes with different doses.
Amen to that. I'm constantly amazed at how much psychiatrists, magazines, webpages, etc. -- experts and amateurs alike -- pretend that they actually understand what's going on with neurotransmitters.
It seems to me that psychiatry as a whole, starting with Freud, has always tended to attribute knowledge and abilities to itself that it does not possess. IMO this has traditionally been a problem with physicians in general, to a degree, but most pronounced in psychiatry (and some other branches of medicine, such as orthopedic surgery).
I think, in my lifetime, both psychiatrists and doctors in general have gotten better about this.
Posted by Marty on July 17, 2008, at 16:34:58
In reply to Re: Study highlights Dopamine's dichotomous role, posted by blueboy on July 15, 2008, at 10:34:57
It makes very mucho senses. I can't believe it took so many decades for scientists to find this!.. I sometime wish neuro scientists would work more with engineers (especially computer scientist and the reverse engineering specialists) .. It could helps alot to know HOW to create complex systems before trying to understand (reverse engineer) a system as complex as the brain.
/\/\arty
Posted by Dade on July 19, 2008, at 1:38:54
In reply to Study highlights Dopamine's dichotomous role, posted by jrbecker76 on July 10, 2008, at 19:29:10
"disruptions in dopamine neurotransmission in an adjacent region may be a mechanism for excessive reward-seeking in conditions like addiction."
Heres where i have a curiosity with. Say someone who fails in life/is mood disordered, takes, say a stimulant drug/alcohol and feels remarkably better and functions better, but is also unable to stop using, one could say they are altering the mentioned brain area to a more normal state. Now we also know that chronic use of these drugs causes changes to this brain area, so it's a catch 22?
Posted by maree on July 22, 2008, at 1:01:37
In reply to Re: Study highlights Dopamine's dichotomous role, posted by blueboy on July 15, 2008, at 10:34:57
>" It seems to me that psychiatry as a whole, starting with Freud, has always tended to attribute knowledge and abilities to itself that it does not possess. IMO this has traditionally been a problem with physicians in general, to a degree, but most pronounced in psychiatry (and some other branches of medicine, such as orthopedic surgery)."Probably because the mistakes a psyche may make, that cause death (likely suicide), can less be blamed on them than if a person dies as a result of taking THIS medication, or bled to death in the OR. They can therefore expound on theories that have no real factual base, because their so called "knowledge" cannot be used to beat them with, later, if it proves wrong.
This is the end of the thread.
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